Gas-powered aspirators are well known devices useful for providing suction to clear patients' lungs, for removing secretions or blood, and to allow insertion of an airway device, or for keeping the patient's airway open for respiration or ventilation. For emergency use, the gas-powered aspirators are particularly advantageous, since they do not require the electrical sources for powering motors and pumps, but instead, operate from a source of compressed air or oxygen, normally available in emergency or rescue vehicles and ambulances.
Commonly, gas-powered suction devices are driven by using compressed oxygen which flows past a restricted passageway or orifice to create a venturi effect, which creates the vacuum suction. As convenient as such portable and emergency suctioning equipment is, the aspirators used heretofore have not shut off or terminated the oxygen flow when adequate vacuum is achieved in the device, but instead, require an operator to manually turn off the oxygen supply valve, which often, is not convenient, especially in an emergency situation. Yet, when the valve is not off, there is excessive consumption of oxygen as the flow continues, even though there is no immediate demand for the suction. It is to the elimination of this problem, and the conservation of oxygen, as well as for operator convenience, that the device of the present invention is directed.